What does it take to keep a TV show from being canceled?

Good, old-fashioned letter-writing campaigns have saved a number of shows from the chopping block. In fact, the first show fans ever saved from cancellation, "Star Trek: The Original Series," was the result of an organized letter-writing campaign. When fans were working to keep the show on the air in 1968, they didn't have the benefit of the Internet. Instead, Bjo and John Trimble, who were experienced at running and promoting art shows, used their marketing prowess to organize fan letters. They sent a "how-to" letter out to fellow Trekkies, encouraging them to write in to NBC to support the show. The network listened, and "Star Trek: The Original Series" went on to air for an additional season.

Of course, in the age of the Internet, campaigns like this are easier to organize. Fans of the FOX series "Friday Night Lights," for example, went beyond letters and even e-mails. They organized a Facebook group and online petitions to support the show, which continued for five seasons despite low ratings.

It wasn't just online action that saved "Friday Night Lights," though. The latest trend with fan action has gone beyond just e-mails, letters and petitions. Fans still barrage network executives with letters of support, but it's becoming more and more common to include some kind of symbol that represents the show to really grab executives' attention.

In the case of "Friday Night Lights," fans sent light bulbs to network executives. Gimmicks have helped save other shows, too. To show their support, "Roswell" fans sent in bottles of Tabasco sauce (a favorite of one of the show's characters), and fans of "Jericho" sent CBS a whopping 20 tons of peanuts (in response to a character's declaration of "Nuts!" in the season finale).

Gimmicks aren't always successful, though, even when they've worked in the past. Tabasco sauce helped keep "Roswell" on the air for three seasons, but low ratings did it in after that. So what else can help a show survive?